1,721,834 research outputs found
Generazione di dati multidimensionali e loro elaborazione mediante modelli multi-way non-lineari per il monitoraggio della qualità degli alimenti
No full textPer migliorare la verifica dell’autenticità degli alimenti, a fronte di possibili adulterazioni o falsa etichettatura, questo progetto intende valutare la qualità, la genuinità e il deterioramento degli alimenti tramite l’analisi di dati multi-way utilizzando modelli di classificazione non lineari
Curing Viscosity of HTPB-Based Binder Embedding Micro and Nano-Aluminum Particles
Full text linkAluminum is used as a metal fuel in energetic materials for the improvement of propulsion performance and density. Both nano-sized and micrometer-sized activated powders represent valuable options in order to improve metal combustion properties, each possessing advantages and drawbacks. These ingredients bear peculiar properties (namely, higher specific surface, coatings, or surface characteristics) which generate high mixing viscosity once suspended in a polymer as well as altered mechanical properties of the final product. Four different powders dispersed in a polymer binder are taken into consideration and the evolution of viscosity in time during the curing process is investigated. The suspending medium is represented by a mixture of hydroxyl-terminated polybutadiene (HTPB), isophorone diisocyanate (IPDI) and dioctyl adipate (DOA). Viscosity was measured for 5h on samples under isothermal curing at 60°C. Non-isothermal DSC kinetic analyses were also performed using the Kissinger method. It was found that, for the test conditions, a size reduction of metal particles slowed down the increment rate of curing viscosity while some peculiar coatings, such as fatty acids, introduced opposite trends
Genotype to Chemotype Analysis in Sage (Salvia officinalis L., Lamiaceae)
No full textChemotypes (or chemovars) are chemically distinct entities within a plant species based on genetic variation. Their occurrence is in mono- and sesquiterpenes (principal constituents of essential oils) exceptionally frequent. In almost all chemotypes the genetic background of their formation is still unknown. Salvia officinalis L. (garden sage, Dalmatian sage, Lamiaceae), a medicinal and aromatic plant whose numerous different bioactivities are partly based on its essential oil, is a prime example of the occurrence of a multitude of chemotypes. The genetic resources already available for Dalmatian sage (gene sequences and protein structures of monoterpene synthases, gene regulation, etc.) permit here an in depth elucidation of the genetic background of chemotype formation. A population of garden sage from Central Albania will be the model population in focus to study this background because this population is polymorphic in a specific sensorially important essential oil composition. In the beginning, the natural variation of the target genes (different monoterpene synthases) on the genomic level will be compiled including their 5Ą ̄ and 3Ą ̄ UTRs and the promoter regions. The major difficulty is the occurrence of multiple copies of each gene in the genome whose exact number is still unknown. Therefore, a complex qPCR and sequencing approach is foreseen to detect haplotypes within individuals. After an inventory of haplotypes, an extensive analysis of the transcriptome will follow in order to find out which haplotypes are expressed in different chemotypes and plant tissues. In a next step, the association between expressed haplotypes and chemotypes will be studied first in silico and then in an in planta transient expression system. Furthermore, promoter regions will be analyzed, because differences here could also be responsible for the chemical polymorphisms. Deletion analysis of the promoter regions shall further clarify, which minimal requirements are necessary for gene expression of monoterpene synthases. Two bioactive monoterpenes in sage, alpha and beta-thujone, have potential neurotoxic effects when consumed in excess. Therefore, the thujone chemotypes will be studied in a neuronal cell culture assay to determine if the chemotypes show different activity in this assay and if the plant extract has the same activity as pure compounds. In the end our results will not only explain the correlation between genotype and a specific chemotype in Dalmatian sage but shall also enable a faster and straightforward exploration of further genotype\chemotype correlations in Dalmatian sage and many others of the numerous essential oil delivering plant species from the same family because in many of these closely related species, the basic genetic principle of chemotype could be similar. The known correlation between genotype and chemotype may also be important for quality assurance systems in pharmacy and the food sector, because this work could pave the way towards enables molecular markers to determine a specific chemotype without chemical analysis
Parallel packing code for propellant microstructure analysis
Full text linkIn recent years, packing codes have become a successful alternative to experimental data collection for microstructure investigation of heterogeneous materials. Composite solid rocket propellants are interesting representatives of this category, consisting of a mix of fuel and oxidizer powders embedded in a polymeric binder. Their macroscopic properties are strictly dependent on the peculiar microstructure, which influences mechanical, combustion, as well as physical features. This work addresses algorithm development, validation, and scalability of POLIPack, a parallel packing code based on the Lubachevsky–Stillinger algorithm, developed at the Space Propulsion Laboratory (SPLab) of Politecnico di Milano. The application can reproduce the organization of spheres of any diameter inside a cube with periodic boundary. In addition to the general code description, the paper identifies a collision condition not addressed by the original Lubachevsky's algorithm (here called back impact), introduces a novel post-impact handling granting a minimum separation velocity between particles, and presents a parallelization approach based on OpenMP shared memory paradigm. Monomodal and bimodal packs have been compared to experimental data through statistic descriptors and packing maps
Eserciziario di Botanica Farmaceutica
No full textLibro di esercitazioni per gli studenti del corso di laurea in Farmaci
Essential oil comparison of Hypericum perforatum L. subsp. perforatum and subsp. veronense (Schrank) Ces. From central Italy
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Uncertainty Propagation in Post-Firing Analysis of SRM Internal Ballistics
No full textPost-firing analysis of solid rocket motors enables the identification of important propulsion parameters such as characteristic velocity, discharge coefficient, throat erosion, burning time, and other details, depending on the degree of complexity involved in the analysis. Firing data can have different sources. Test-bench firings are usually carried on for evaluation purposes during design processes, prototype evaluation, or routine quality check in propellant production. Mission-related data may be obtained from in-flight streaming. In this respect, some types of information are not always available for in-flight tests. Throat erosion measurements are not accessible or the propulsion unit might not be fully instrumented, in case of production flights. The accuracy featuring analysis results are influenced by both uncertainty of available data (e.g. random or systematic errors) and lack of knowledge for some parameters. The present work applies a methodology for uncertainty propagation to a simplified post-firing tool. The post-processing algorithm is based on a zero-dimensional framework capable of deriving characteristic velocity, thrust coefficient, throat erosion, and burning time. Code implementation and verification are presented. An example of uncertainty analysis is reported for a limited number of sources, both epistemic and aleatory. Propagation is traced using a Monte Carlo method and Latin hypercube sampling
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